EPA’s oral reference dose (daily oral exposure likely to be without an appreciable risk of deleterious non-cancer effects during a lifetime) of diethyl phthalate is 0.8 mg/kg/day.

Diethyl phthalate is regulated as a denaturant for alcohol (27 CFR 21.106) and it is often used at a concentration of 0.5% to denature ethanol used in cosmetic products.

Although several cases of allergy to diethyl phthalate have been reported, attempts to sensitize skin in studies with animals and human volunteers have not been successful.

In a randomly selected adult reference U.S. population, the urinary metabolite monoethyl phthalate (median, 305 µg/L) occurred in much greater concentrations than the metabolites of six other phthalate derivatives.

The absorption rate of diethyl phthalate was reported to be much slower through human skin than through rat skin in vitro.